CN112912942B

CN112912942B - Orthogonal isolation exciter with field steering

Info

Publication number: CN112912942B
Application number: CN201980050248.XA
Authority: CN
Inventors: E·N·鲁迪; K·克林克默尔; J·希尔特纳; D·科斯特洛; S·E·克鲁格; L·科伊拉克; S·摩根; D·范德韦德
Original assignee: Elucent Medical Inc
Current assignee: Elucent Medical Inc
Priority date: 2018-06-05
Filing date: 2019-06-04
Publication date: 2024-03-08
Anticipated expiration: 2039-06-04
Also published as: US10278779B1; EP3803825A1; US20230263576A1; US20190388178A1; US20230157763A1; CN112912942A; US11540885B2; JP2021526890A; US11185375B2; US20190365478A1; EP3803825A4; US20220054203A1; WO2019236600A1; US11666391B2

Abstract

Systems, devices, components, and methods for generating an excitation signal to, for example, activate a remotely located tag are provided herein. The systems, devices, assemblies, and methods may be used in a variety of applications, including medical applications for locating tags within a subject.

Description

Orthogonal isolation exciter with field steering

The present application claims priority from U.S. provisional application Ser. No. 62/680,750, filed on 5, 6, 2018, which is incorporated herein by reference in its entirety.

Technical Field

Systems, devices, assemblies, and methods for generating an excitation signal to, for example, activate a remotely located marker tag are provided herein. The systems, devices, assemblies, and methods may be used in a variety of applications, including medical applications for locating tags within a subject.

Background

A common and serious challenge for many medical procedures is the accurate positioning of the treatment area. For example, locating lesions (such as tumors) to be treated (including surgical resections) continues to present challenges to the medical community. Existing systems are expensive, complex, time consuming and often unsatisfactory to the patient. Surgical treatment of breast lesions accounts for these problems.

A common technique in breast tumor surgery is guidewire positioning of lesions. Before removing a lesion, some breast lesions must be precisely preoperatively located. The guidewire is positioned to mark the location of the breast abnormality. The procedure ensures greater accuracy of breast biopsies or tumor resections. The surgeon typically uses a guidewire to direct the tissue to be removed. Guidewire positioning is typically performed in a radiology department of a hospital or surgical center. Mammograms (or ultrasound images in some cases) are taken to show the location of breast abnormalities. The patient remains awake during placement of the guidewire, but breast tissue is anesthetized to reduce or avoid pain caused by the needle or guidewire. Pressure or pull feel may be felt during guidewire placement. Once the image has been taken and the tissue has been anesthetized, the radiologist will aim at the breast abnormality using a needle. The tip of the needle is placed in a position that the surgeon needs to find to remove the proper tissue. A thin guidewire is passed through the needle and out of the needle head to be secured at the target tissue. The needle is removed leaving the guidewire behind. After the guidewire is in place, the patient takes a further mammogram to check if the guidewire tip is properly positioned. If the guidewire is not in the correct position, the radiologist will reposition and recheck to ensure proper placement. When the guidewire is finally placed, it will be secured in place with tape or bandages. The guidewire positioning procedure may take about one hour and is typically scheduled to be performed several hours prior to biopsy or tumor resection. Thus, patients often have to wait several hours for surgery to occur, with the guide wire being present in their body and protruding from their skin. During surgery, the guide wire is removed along with some breast tissue. This process takes hours, involves multiple imaging steps, and is inconvenient and unpleasant for the patient and expensive.

A similar type of procedure is performed to locate the lung nodules prior to resection. In some cases, where it may be difficult to locate a lung nodule in a conventional open surgery or thoracoscopy, a hooked guidewire, visible dye injection, or radionuclide is placed within or near the nodule in an attempt to improve positioning prior to removal of the nodule. This procedure is typically performed in a Computed Tomography (CT) suite prior to nodule removal. The patient is then transported to the operating room, the surgeon cuts the guidewire, uses the radionuclide detectors, or uses visual landmarks to locate and remove the nodules.

In other types of surgical and medical procedures, it may be difficult for a physician to locate a target prior to removal or manipulation. Examples of this include removing bumps, effusions, foreign bodies, or diseased tissue. Other times, catheter placement or other percutaneous procedures are performed without direct visualization or without a specific guiding modality. Performing surgery without precise guidance may increase the amount of damage to normal tissue and decrease the functional status of the patient.

Percutaneous biopsy is a widely accepted, safe procedure performed in almost every hospital. Biopsies typically require placement of a coaxial introducer needle through which the biopsy device is placed into the target. Many lesions removed, pierced, or treated as described above have previously been successfully biopsied percutaneously. Placement of the introducer needle for biopsy enables placement of a fiducial or other positioning system without causing additional tissue trauma that the patient would not otherwise suffer.

Many other medical devices and procedures may benefit from improved tissue localization. These procedures include any procedure or detection of degradation due to any body movement, such as heart movement, respiratory movement, movement produced by the musculoskeletal system, or gastrointestinal/genitourinary movement. Examples of such procedures include external beam radiation therapy, placement of brachytherapy seeds, imaging detection (including but not limited to CT, MRI, fluoroscopy, ultrasound, and nuclear medicine), biopsy in any manner, endoscopy, laparoscopic and thoracoscopic procedures, and open surgical procedures.

There is a need for improved systems and methods for tissue localization of medical procedures.

Disclosure of Invention

Systems, devices, components, and methods for generating an excitation signal to, for example, activate a remotely located tag are provided herein. The systems, devices, assemblies, and methods may be used in a variety of applications, including medical applications for locating tags within a subject. While the following description illustrates the present invention using an example of a human surgical procedure, it should be understood that the present invention is not so limited and includes veterinary applications, agricultural applications, industrial applications, mechanical applications, military applications (e.g., sensing and removing hazardous materials in objects or areas), aerospace applications, and the like.

In some implementations, provided herein is a system comprising one or more or each of the following: a) One or more tags; b) A remote activation device (e.g., an exciter assembly) that generates a magnetic field (e.g., a time-varying magnetic field) within an area of the tag, the remote activation device comprising four or more exciter coils, each exciter coil configured to cause current to flow in a clockwise or counter-clockwise direction, such that the magnetic field generated by the remote activation device can be selectively generated substantially in any or all of an X-direction or a Y-direction or any or all of an X-direction, a Y-direction, and a Z-direction (e.g., to ensure that the tag can be excited for multiple or any angle at which the tag can be placed); and c) a plurality of sensors configured to detect signals from the one or more tags when the one or more tags are exposed to the magnetic field. In some embodiments, the four or more excitation coils are connected in series. In some embodiments, four of the excitation coils are presented in a two-row arrangement centered on coordinates (X1, Y1), (X1, Y2), (X2, Y1), and (X2, Y2). In some embodiments, the remote activation device (e.g., excitation component) includes three current flow configurations: a) All currents are in the clockwise direction to simulate an excitation coil aligned with the direction perpendicular to the Z-axis; b) An excitation coil centered on (X2, Y1), (X2, Y2) causes current to flow in a counterclockwise direction to simulate an excitation coil aligned with the X axis; and c) a drive coil centered on (X1, Y2), (X2, Y2) causes current to flow in a counter-clockwise direction to simulate a drive coil substantially aligned with the Y axis. In some implementations, the remote activation device (e.g., excitation component) includes a plurality of relays that provide switching functionality to accomplish a current direction change (polarity) but maintain the excitation frequency by switching additional capacitive reactance. In some implementations, the switching function inserts additional series capacitive reactance via the capacitive element as the total inductance increases so that the tuning center frequency is maintained at the excitation frequency (e.g., when 4 coils are employed, the total inductance of the 4 coils varies with each coil or coil versus the direction of the internal current). In some embodiments, the capacitive element includes a plurality of capacitors (e.g., to better accommodate voltage potentials at resonance and/or to provide greater flexibility in frequency tuning). In some embodiments, the remote activation device further comprises a balun proximate the excitation coil. The balun eliminates common mode currents that would otherwise generate unwanted electric field components that would otherwise reduce accuracy. The balun also provides impedance transformation to match the real component of the coil impedance to the real component of the transmission line, typically 50 ohms. In some embodiments, the balun has eight turns on the primary side (amplifier side) and four turns on the secondary side (coil side). In some embodiments, the system further comprises an amplifier in electronic communication with the remote activation device. In some embodiments, the system further comprises a computer that controls magnetic field generation and sensor detection. In some embodiments, the computer includes a trapping algorithm (e.g., embodied in software enabled on a processor) that adjusts the magnetic field orientation to identify optimal detection of (and power supply to) one or more tags.

In some embodiments, provided herein is an apparatus and system comprising: a remote activation device that generates a magnetic field within an area of a tag, wherein the remote activation device comprises: a) A base substrate (e.g., a substantially planar surface), b) four or more excitation coils attached to the base substrate, wherein each of the excitation coils is configured to flow a current in a clockwise or counter-clockwise direction such that the magnetic flux can be selectively generated substantially in an X or Y direction; and c) a plurality of witness station components attached to the base substrate, wherein each of the witness station components comprises a witness coil having a sensing axis and comprising: i) A core having a non-coil proximal end, a wireless coil distal end, and a central region, wherein the core comprises metal, and ii) a coil winding wound on the central region of the core, wherein each of the witness station components is oriented on the base substrate such that the sensing axis of each of the witness coils: a) Extending from the proximal end to the distal end of the core, and B) orthogonal or substantially orthogonal to each of: i) Each of the four or more excitation coils, and/or ii) the magnetic flux in each of the X-direction and the Y-direction.

In certain embodiments, provided herein is an apparatus and system comprising: a remote activation device that generates a magnetic field within an area of a tag, wherein the remote activation device comprises: a) A base substrate, b) at least one excitation coil attached to the base substrate, the excitation coil generating a magnetic flux; and c) a plurality of witness station components attached to the base substrate, wherein each of the witness station components comprises a witness coil having a sensing axis and comprising: i) A core having a non-coil proximal end, a wireless coil distal end, and a central region, wherein the core comprises metal, and ii) a coil winding wound on the central region of the core, wherein each of the witness station components is oriented on the base substrate such that the sensing axis of each of the witness coils: a) Extending from the proximal end to the distal end of the core, and B) orthogonal or substantially orthogonal to each of: i) The magnetic flux, and/or ii) the at least one excitation coil. In a particular embodiment, the at least one excitation coil is configured to selectively cause current to flow in a clockwise or counter-clockwise direction. In other embodiments, the sensing axis of each of the witness coils is substantially orthogonal to the magnetic flux for the clockwise direction and the counter-clockwise direction.

In certain embodiments, the system further comprises the tag. In other embodiments, provided herein are methods of detecting a tag in a subject using such systems and devices.

In certain implementations, each of the excitation coils includes a central plane, and wherein each of the witness components is also oriented on the base substrate such that the sensing axis of each of the witness coils: c) Coplanar with the center plane of each of the excitation coils. In a particular embodiment, the magnetic flux does not induce a signal in the witness coil when generated substantially in the X-direction and/or the Y-direction.

In other embodiments, each of the witness components further comprises: i) A first witness coil stent and a second witness coil stent, and ii) a first elastomeric portion and a second elastomeric portion, and wherein the wireless coil proximal end of the core is secured between the first witness coil stent and the first elastomeric portion, and wherein the wireless coil distal end of the core is secured between the second witness coil stent and the second elastomeric portion. In further embodiments, the first and second witness coil stent each comprise at least one adjustment portion. In other embodiments, the at least one adjustment portion comprises at least one screw and/or at least one rod. In certain embodiments, provided herein are methods of adjusting the witness coil with the adjustment portion such that a sensing axis of the witness coil is orthogonal or substantially orthogonal to the magnetic flux and/or the at least one or at least four excitation coils.

In some implementations, the at least one adjustment portion allows adjustment of the sensing axis of each of the witness coils such that the sensing axis is orthogonal or substantially orthogonal to the magnetic flux in each of the X-direction and the Y-direction. In further embodiments, the magnetic flux can also be selectively generated substantially in a Z-direction, and wherein each of the witness components is oriented on the base substrate such that the sensing axis of each of the witness coils is orthogonal or substantially orthogonal to the magnetic flux in the Z-direction. In further embodiments, the magnetic flux does not induce a signal in the witness coil when generated substantially in the Z-direction. In further embodiments, the at least one adjustment portion allows adjustment of the sensing axis of each of the witness coils such that the sensing axis is orthogonal or substantially orthogonal to the magnetic flux in each of the X-direction, the Y-direction, and the Z-direction. In some embodiments, the metal comprises ferrite.

In other implementations, each of the witness components is oriented on the base substrate such that the sensing axis of each of the witness coils is orthogonal or substantially orthogonal to each of the four or more excitation coils. In some implementations, each of the witness station components is oriented on the base substrate such that the sensing axis of each of the witness coils is orthogonal or substantially orthogonal to the magnetic flux in each of the X-direction and the Y-direction. In further embodiments, the four or more excitation coils are four excitation coils or six excitation coils. In other embodiments, the four excitation coils are presented in a layout that is arranged in two rows centered on coordinates (X1, Y1), (X1, Y2), (X2, Y1), and (X2, Y2). In further embodiments, the remote activation device comprises three current flow configurations: a) All currents are in a clockwise direction to simulate an excitation coil aligned or substantially aligned with a plane perpendicular to the Z-axis; b) The excitation coil centered on (X2, Y1), (X2, Y2) causes current to flow in a counterclockwise direction to simulate an excitation coil aligned or substantially aligned with the X-axis; and c) the excitation coil centered on (X1, Y2), (X2, Y2) causes current to flow in a counter-clockwise direction to simulate an excitation coil aligned or substantially aligned with the Y-axis.

In some embodiments, the sensing axis of the witness coil is substantially orthogonal when the isolation between the at least four excitation coils and the witness coil is 60dB or greater in the X-direction and the Y-direction. In other embodiments, the sensing axes of the witness coils are substantially orthogonal when the isolation between the at least four excitation coils and the witness coils is 60dB or greater in the X, Y, and Z directions.

Also provided herein are uses of any of the above systems (e.g., for detecting the position of a tag in an object, for detecting the position of a tag relative to a medical device, etc.).

Also provided herein is a method of identifying a location of a tag, the method comprising: a) Providing any of the systems described herein; b) Placing the tag in an object; c) Generating a magnetic field with the activation device; and d) identifying the location of the tag in the object by collecting information emanating from the tag using the witness station. In some embodiments, the location or comprises a relative location or distance of the tag from the medical device.

In certain embodiments, provided herein is a system and apparatus comprising: an excitation assembly that cycles between generating at least a first magnetic field, a second magnetic field, and a third magnetic field (e.g., first, second, third, fourth, fifth, sixth, seventh, and/or eighth magnetic fields) to cause the tag to generate a signal, wherein the excitation assembly comprises: a) a base substrate, B) a first excitation coil attached to the base substrate, wherein upon generation of the first magnetic field, the second magnetic field, and the third magnetic field, current in the first excitation coil flows in a clockwise direction, C) a second excitation coil attached to the base substrate, wherein upon generation of the first magnetic field and the second magnetic field, current in the second excitation coil flows in a clockwise direction, and upon generation of the third magnetic field, current in the second excitation coil flows in a counter-clockwise direction, D) a third excitation coil attached to the base substrate, wherein upon generation of the first magnetic field and the third magnetic field, current in the third excitation coil flows in a clockwise direction, and upon generation of the second magnetic field, current in the third excitation coil flows in a counter-clockwise direction; and E) a fourth actuator attached to the base substrate, wherein current in the fourth actuator coil flows in a clockwise direction when the first magnetic field is generated and flows in a counterclockwise direction when the second and third magnetic fields are generated.

For example, the excitation coil may be wound using litz wire to minimize resistive losses due to skin effects that occur with increasing frequency. The number of turns is typically chosen to maximize the coil "Q" (inductance/resistance ratio). An example coil is litz wire comprising 100 strands of 38AWG wire. At 134.5KHz, the inductance of a single coil measures about 1.1mH, and Q (ratio of inductance to resistance) measures over 500. Other coil configurations using other wires with different inductance and Q values may be used. However, it is generally desirable to keep the "Q" as high as possible to minimize resistive losses that result in efficiency losses and greater thermal heating.

In some embodiments, provided herein is a system and apparatus comprising: a) a base substrate, b) a first excitation coil, a second excitation coil, a third excitation coil, and a fourth excitation coil, the first excitation coil, the second excitation coil, the third excitation coil, and the fourth excitation coil being attached to the substrate and configured to generate a magnetic field to cause a tag to generate a signal, c) a balun circuit electrically connected to the first excitation coil, the second excitation coil, the third excitation coil, and the fourth excitation coil.

In a particular implementation, each of the second excitation coil, the third excitation coil, and the fourth excitation coil is operatively connected to a switch that controls a direction of current flow through the excitation coils. In certain implementations, each switch includes a relay element, a PIN diode, a field effect transistor, or other solid state switching device. In a particular implementation, each switch additionally switches at least one capacitor (e.g., two capacitors) into the circuit to keep the resonant frequency of the series combination of excitation coils constant despite variations in the total coil inductance caused by coil polarity changes.

The inductance of the exemplary excitation coil system measures 1.1mH for each individual coil, where Q >500. The inductance of the series combination of 4 coils (e.g., as shown in fig. 4A) varies with the polarity of the coils (current direction) due to the interaction of the magnetic fluxes generated by each coil. For the current direction depicted in fig. 5, the inductance of the series combination of all 4 exemplary coils, all of which caused current to flow in the clockwise direction, was measured to be 3.9mh, q=435. For the current direction depicted in fig. 6, the inductance of the series combination of all 4 exemplary coils was measured to be 4.6mh, q=500, with coils a and B flowing current in the clockwise direction and coils C and D flowing current in the counterclockwise direction. For the current direction depicted in fig. 7, the inductance of the series combination of all 4 exemplary coils was measured at 4.3mh, q=473, where coils a and C caused current to flow in the clockwise direction and coils B and D caused current to flow in the counterclockwise direction. When the coil polarity changes, this change in total inductance needs to be switched into the appropriate compensation capacitor.

In some embodiments, the components of the relay or switch and associated capacitors may be placed on a ceramic substrate to provide a secure installation, excellent dielectric properties, and also act as a heat sink to reduce localized heating of the individual components.

In some embodiments, the systems and devices further comprise: a plurality of witness coils or witness station components attached to the substrate and configured to detect the signal from the tag. In some embodiments, the witness coil is positioned such that the axis of the coil is coplanar with the center plane of the excitation coil. In this plane, the magnetic flux generated by the exciter is orthogonal to the sensing axis of the witness coil for each combination of the aforementioned coil current directions. The quadrature exciter current does not induce a signal into the witness coil and therefore provides isolation between the exciter coil and the witness coil. Such isolation is typically required to achieve the required system dynamic range so that very weak tag signals can be detected in the presence of very large exciter magnetic fields. This isolation is also important because crosstalk between the excitation coil and witness coil would otherwise greatly hinder navigation, because the crosstalk term would contribute significant signals from the same magnetic dipole (exciter) to all witness coils, and thus the witness coils would lose their spatial independence. Another point is that the presence of the z-axis oriented actuator can significantly distort the z-axis component of the tag (and transmitter) magnetic field, making it less useful for navigation.

In further embodiments, the plurality of witness coils or plurality of witness station components comprises six to thirty witness coils (e.g., 6 … 9 … 12 … 20..or 30). In additional embodiments, the plurality of witness coils: i) Located on opposite sides of the base substrate, but not adjacent to the opposite sides, and/or ii) each positioned to be alternately oppositely oriented along the X and y axes relative to the other witness coils. This positioning minimizes crosstalk between witness coils, thereby reducing the degree of crosstalk compensation applied (e.g., by mathematical solver software).

In some implementations, the system and device also include a plurality of printed circuit boards, wherein each of the plurality of witness coils is operatively connected to one of the plurality of circuit boards. In certain embodiments, each circuit board includes at least two capacitors and at least one balun circuit. In certain embodiments, the systems and devices further comprise the tag.

In certain embodiments, the systems and devices further comprise a balun circuit electrically connected to the first excitation coil, the second excitation coil, the third excitation coil, and the fourth excitation coil. In further embodiments, the system and apparatus further comprise a cable harness electrically connected to the balun circuit. In further embodiments, the system and apparatus further comprise a plurality of witness coils attached to the substrate and configured to detect the signal from the tag, wherein the plurality of witness coils are electrically connected to the cable bundle.

In some embodiments, the systems and devices further comprise at least one self-test emitter. In other embodiments, the systems and methods further include a cap, wherein the cap cooperates with the base substrate to enclose the first excitation coil, the second excitation coil, the third excitation coil, and the fourth excitation coil therein.

In other embodiments, the system and apparatus further comprise a system electronics housing configured to provide signals to the first excitation coil, the second excitation coil, the third excitation coil, and the fourth excitation coil. In other embodiments, the centers of each of the first, second, third, and fourth excitation coils are spaced apart from each other by at least 5 centimeters (e.g., 5 … 10 … 15 … 25 … 100 … 1000 cm). In other embodiments, the center of each of the first, second, third, and fourth excitation coils is spaced apart from each other by 2-5 times the largest dimension of the coil itself. In certain embodiments, the fourth excitation coil is positioned next to the second excitation coil, and wherein the third excitation coil is positioned next to the first excitation coil and diagonally to the second excitation coil.

In some embodiments, provided herein is a method comprising: a) Placing a system or device disclosed herein under or near a patient with a tag located within the patient, and b) activating the system or device such that a magnetic field is generated, thereby causing the tag to generate a signal.

In some embodiments, provided herein is a system and apparatus comprising a witness station component, wherein the witness station component comprises: a) Witness coil, wherein the witness coil comprises: i) A metal core having a non-coil proximal end, a wireless coil distal end, and a central region, and ii) a coil winding wound on the central region of the metal core, b) a first witness coil leg and a second witness coil leg, and c) a first elastomer portion and a second elastomer portion, wherein the wireless coil proximal end of the metal core is secured between the first witness coil leg and the first elastomer portion, and wherein the wireless coil distal end of the metal core is secured between the second witness coil leg and the second elastomer portion. In certain embodiments, the system or device further comprises a remote activation device (e.g., as described herein), wherein the remote activation device comprises at least one excitation coil. In further embodiments, the systems and devices further comprise: an excitation assembly (e.g., as described herein), wherein the excitation assembly comprises at least one excitation coil.

In further embodiments, the first witness coil stent and the second witness coil stent each include at least one adjustment portion (e.g., two adjustment screws). In some embodiments, the at least one adjustment portion comprises at least one screw and/or at least one rod. In other embodiments, the witness station assembly further includes an electronics portion electrically connected to the witness coil. In other embodiments, the electronic device portion includes at least one capacitor and/or at least one balun circuit. In further embodiments, the electronic device portion comprises a printed circuit board.

In certain embodiments, the witness station assembly further comprises a faraday shield. In other embodiments, the witness station assembly further comprises: i) An electronics portion electrically connected to the witness coil, and ii) a faraday shield. In additional embodiments, the first elastomeric portion and the second elastomeric portion comprise a material selected from the group consisting of: elastomeric polymers and springs.

In some embodiments, the metal core comprises a ferrite core. In other embodiments, the diameter of the metal core is 4 to 25mm (4 … 8 … 12 … 14 … 16 … 25 mm). In certain embodiments, the metal core has a length of 15 to 75mm (e.g., 15 … 30 … 45 … 58 … mm). In a particular embodiment, the coil winding comprises a wire. In other embodiments, the wire is wound 150 to 300 times around the metal core. In further embodiments, the first witness coil stent and the second witness coil stent each comprise a notch configured to mate with the wireless proximal end and/or the wireless distal end of the metal core.

In certain embodiments, provided herein is an apparatus and system comprising: a) An attachment member configured to attach to a handheld medical device having a device tip, wherein the attachment member comprises: i) A proximal end, ii) an angled distal end, wherein the angled distal end comprises a distal opening configured to allow the device tip but not the rest of the medical device to pass therethrough, and iii) a body extending between the proximal end and the angled distal end, and b) a first position emitter and a second position emitter, the first position emitter and the second position emitter being attached to the attachment member.

In certain embodiments, the angled distal end has an angle of at least 35 degrees (e.g., at least 35 … 45 … 65 … 85 … or 95 degrees) relative to a longitudinal axis of the attachment member. In some embodiments, the angled distal end has an angle of about 90 degrees relative to the longitudinal axis of the attachment member. In further embodiments, the first and second position transmitters are attached to (e.g., spaced apart from) the body of the attachment member.

In other embodiments, the systems and apparatus further comprise: c) A display member housing, wherein the display member housing is attached or attachable to the proximal end of the attachment member. In additional embodiments, the systems and devices further include a display component attached to the display component housing, wherein the display component includes a display screen (e.g., an LCD screen) for displaying the position of the implant label within the patient relative to the device tip on the medical device. In other embodiments, the display component housing includes a cable management component. In additional embodiments, the display member housing comprises a housing cone connection. In further embodiments, the proximal end of the attachment member comprises a proximal tapered connector.

In other embodiments, the devices and systems further comprise a first position emitter lead and a second position emitter lead, wherein the first position emitter lead is electrically connected to the first position emitter (e.g., small coil) and the second position emitter lead is electrically connected to the second position emitter (e.g., small coil). In other embodiments, the systems and devices further comprise: c) An adhesive tape sized and shaped to cover at least 50% (e.g., 50% …% …%) of the attachment member body and configured to adhere the attachment member to the medical device. In certain embodiments, the systems and devices further comprise: c) The medical device. In other embodiments, the medical device comprises an electrocautery surgical device.

Definition of the definition

As used herein, the terms "processor" and "central processing unit" or "CPU" are used interchangeably and refer to a device capable of reading a program from a computer memory (e.g., ROM or other computer memory) and performing a set of steps in accordance with the program.

As used herein, the terms "computer memory" and "computer memory device" refer to any storage medium readable by a computer processor. Examples of computer memory include, but are not limited to, RAM, ROM, computer chips, digital Video Discs (DVDs), compact Discs (CDs), hard Disk Drives (HDDs), optical discs, and magnetic tapes. In certain embodiments, the computer memory and computer processor are part of a non-transitory computer (e.g., in a control unit). In certain embodiments, a non-transitory computer-readable medium is employed, wherein the non-transitory computer-readable medium includes all computer-readable media, with the sole exception of a transitory propagating signal.

As used herein, the term "computer-readable medium" refers to any device or system that stores information (e.g., data and instructions) and that provides the information to a computer processor. Examples of computer readable media include, but are not limited to, DVDs, CDs, hard drives, magnetic tapes, and servers for streaming media over a network, whether local or remote (e.g., cloud-based).

As used herein, the term "electronic communication" refers to electronic devices (e.g., computers, processors, etc.) that are configured to communicate with each other through direct or indirect signaling. Likewise, a computer configured to transmit information (e.g., via cable, wire, infrared signal, telephone line, electrical wave, etc.) to another computer or apparatus is in electronic communication with the other computer or apparatus.

As used herein, the term "transmitting" refers to moving information (e.g., data) from one location to another (e.g., from one device to another) using any suitable means.

As used herein, the term "subject" or "patient" refers to any animal (e.g., mammal) that will become the recipient of a particular treatment, including, but not limited to, humans, non-human primates, companion animals, livestock, equines, rodents, and the like. Generally, with respect to a human subject, the terms "subject" and "patient" are used interchangeably herein.

As used herein, the term "subject/patient is suspected of having cancer" refers to a subject that exhibits one or more symptoms indicative of cancer (e.g., a distinct mass or tumor) or is being screened for cancer (e.g., during a routine physical examination). A subject suspected of having cancer may also have one or more risk factors. A subject suspected of having cancer is generally not undergoing cancer detection. However, a "subject suspected of having cancer" encompasses individuals who have undergone a preliminary diagnosis (e.g., a CT scan showing a tumor) but whose stage of cancer is unknown. The term also includes people who have had cancer (e.g., remission individuals).

As used herein, the term "biopsy" refers to a sample of tissue (e.g., breast tissue) that has been removed from a subject in order to determine whether the sample contains cancerous tissue. In some embodiments, biopsies are obtained because the subject is suspected of having cancer. The biopsy tissue is then examined (e.g., by microscopy; by molecular testing) for the presence of cancer.

As used herein, the term "sample" is used in its broadest sense. In a sense, this is meant to include specimens or cultures obtained from any source, as well as biological and environmental samples. Biological samples can be obtained from animals (including humans) and encompass fluids, solids, tissues, and gases. Biological samples include tissues, blood products such as plasma, serum, and the like. However, such examples should not be construed as limiting the type of sample that is suitable for use with the present invention.

As used herein, the term "tag" or "marker tag" refers to an implantable miniature marker that when excited by the time-varying magnetic field of an exciter will emit a "homing beacon" spectrum that is received by the witness coil and used to determine its location. The tags may be programmed to produce a unique spectrum, allowing multiple tags to be implanted and located simultaneously.

Drawings

Fig. 1 shows an exemplary positioning of an excitation assembly, a medical device with a display component attached, and a patient with a tag implanted beside a tumor.

Fig. 2 shows the attachment member 10 attached to a medical device 20 having a device tip 25. The attachment member 10 has two position transmitters 70 located therein. The attachment part 10 is attached to the display part 40 or is integrated with the display part 40.

Fig. 3 shows an exemplary coil configuration of the excitation assembly.

Fig. 4A shows an exemplary excitation assembly 250 attached to a controller 210 via a cable bundle 200. Fig. 4B shows an exemplary witness coil assembly (also known as a witness station assembly) 161. Fig. 4C shows an exemplary witness 160 coil that includes three directions along which a wire is wound to form a coil 167 on a metal core 166.

Fig. 5 shows an exemplary excitation assembly with four excitation coils (coils a-D), wherein current flows in a clockwise direction in all four excitation coils.

Fig. 6 shows an exemplary excitation assembly having four excitation coils (coils a-D), wherein current flows in clockwise direction in coils a and B and counter-clockwise direction in coils C and D.

Fig. 7 shows an exemplary excitation assembly having four excitation coils (coils a-D), wherein current flows in clockwise direction in coils a and C and in counterclockwise direction in coils B and D.

Fig. 8 illustrates an exemplary excitation assembly 250 on top of cap 230. The excitation assembly 250 is shown with the cable bundle 200 routed therein.

Fig. 9 shows an exemplary attachment member 10 having an angled distal end 300 through which the distal tip 25 of the medical device 20 is inserted.

Fig. 10A shows distal end 25 of medical device 20 after initial insertion through angled distal end 300 of attachment member 10. Fig. 10B shows the attachment member wires 60 prior to attachment to the cable management member 315 of the display member housing 330. Fig. 10B shows the attachment member wires 60 prior to attachment to the cable management member 315 of the display member housing 330. Fig. 10B also shows a housing cone connector 340 into which the proximal cone connector 350 of the attachment member 10 is inserted. The cable management component 315 has two clips that attach to the attachment component wire 60 and the medical device wire 50 and align the attachment component wire 60 and the medical device wire 50.

Fig. 11 shows an exemplary attachment member 10 attached to a display member housing 330. The attachment member 10 has a pair of position transmitters 70 connected to position transmitter lead wires 72 inside the tube 360. The attachment member also has an angled distal end 300 with a distal opening 305 that allows the tip of a surgical or other device to be inserted therein. The display member housing 330 has a cable management member 315 that is comprised of a pair of clips for holding insulated conductors.

Fig. 12 shows an exemplary attachment member 10 attached to a display member housing 330 in which a display member 40 is located. A display cover 370 is shown for securing the display assembly 40 within the display assembly housing 330. Also shown is an adhesive tape 380 that is shaped and sized to fit inside the attachment member and to help secure the medical device to the attachment member.

Fig. 13A shows a proximal tapered connector 350 of the attachment component 10 configured to be push-fit into a housing tapered connector 340 of the display component housing 330. Fig. 13B shows a close-up view of portion a of fig. 13A, including a cable management cone 317 that is part of the cable management component 315 and is designed to be inserted into a cone connection hole 319 of the display component housing 330. The cable management cone 317 includes a flat portion 318 for locking the angular position.

Fig. 14 illustrates an exemplary system for locating a tag implanted in a patient. The system includes an excitation assembly that emits a signal that activates a tag within a patient. The system electronics housing is shown as a mobile cart that transmits signals to the excitation assembly and receives and processes signals from the tag within the patient. The guidance to the surgeon is displayed on the display component and on a screen on the housing of the system electronics.

Detailed Description

Systems, devices, components, and methods for generating an excitation signal to, for example, activate a remotely located tag are provided herein. The systems, devices, assemblies, and methods may be used in a variety of applications, including medical applications for locating tags within a subject. While the present description focuses on medical use in human tissue, it should be understood that the systems and methods have broader uses, including non-human uses (e.g., for non-human animals such as livestock, companion animals, wild animals, or any veterinary setting). For example, the system may be used in environmental, agricultural, industrial, etc. settings.

A. Solving variable alignment of external coil (e.g., tag coil) with excitation assembly

In some embodiments, the actuator is configured to provide power to the tag independent of alignment of the coil of the tag with the actuator. For example, in some embodiments, the power transfer to the tag may depend on the relative orientation of the exciter magnetic field and the tag. In some such embodiments, without corrective action, the tag may collect power from only the field portion aligned with the coil of the tag (e.g., the ferrite core coil contained in the tag). This problem can be solved by including a plurality of actuators capable of generating all three orthogonal directions of the magnetic field. However, this results in a thicker assembly and prevents both suppressing the primary excitation coil (e.g., located in the excitation assembly) to the sense coil coupling (also located in the excitation assembly) (see section B below) and suppressing the secondary field coupling between the tag/transmitter and the excitation coil, which in turn is coupled to the sense coil and does not facilitate positioning of the tag or transmitter (see section C below). To address this challenge, provided herein is a configuration of an excitation assembly that provides a mechanism to change the orientation of a magnetic field with an excitation coil that can be deployed in only one magnetic direction.

In some embodiments, this is achieved by having multiple coils in the excitation assembly (see, e.g., fig. 4A) and setting the direction of current flow within each coil to be clockwise or counterclockwise (see, e.g., fig. 5-7). In some embodiments, the coils are connected in series such that the same current flows in each coil. In some embodiments, the coil layout includes four coils arranged in two rows centered on the (X1, Y1), (X1, Y2), (X2, Y1), and (X2, Y2) coordinates, with three sets of current flow configurations: configuration 1: all currents are clockwise to simulate an excitation coil aligned with a plane perpendicular to the Z-axis; configuration 2: a coil centered on (X2, Y1), (X2, Y2) flows current in a counter-clockwise direction to simulate an excitation coil aligned with the X axis; and configuration 3: coils centered on (X1, Y2), (X2, Y2) let current flow in a counter-clockwise direction to simulate an excitation coil aligned with the Y axis. Any number of other coil configurations may be employed. To increase efficiency, it is desirable (although not necessary) to minimize the number of components and the overall complexity of the design. However, in some implementations, it may be desirable to have more than four coils (e.g., 6, 8, 10, 16, etc.) in the excitation assembly to provide more flexibility in changing the field directivity, albeit at the cost of complexity of the system.

When the same current flows through all coils in each configuration, there is less variation between the configurations required to adjust the coils in the excitation assembly for each configuration. This is because the effect of one excitation coil on the other excitation coils depends on the state of the first excitation coil (open circuit, current carrying, etc.).

To provide optimal performance, the area of the excitation coil should be maximized and the distance between the centers of the coils should be maximized. For the same applied current, a larger area coil provides a higher magnetic field. Coils at larger distances provide larger changes in direction for configurations 2 and 3.

Fig. 3 provides an exemplary schematic of a four coil excitation assembly in some embodiments of the invention, with four coils labeled as coil a, coil B, coil C, and coil D (see fig. 4A).

For medical use, where the excitation assembly is disposed under the patient in a flat planar mode (e.g., a pad), the clinically preferred system geometry requires that all four coils be placed in close proximity to each other. As a result, the magnetic coupling between the coils varies with the individual coil polarities, and therefore the total inductance of all four coils in series varies with the combination of coil polarities. Thus, optimal performance will necessarily balance competing factors. To compensate for this, in some embodiments, a switching system is employed in which an additional series capacitive reactance is inserted as the total inductance increases so that the tuning center frequency is maintained at the desired excitation frequency. In the preferred embodiment shown in fig. 3, a relay is used for switching. Other embodiments may employ solid state switching methods, such as PIN diodes. Any suitable mechanism for effecting handoff may be employed.

In some embodiments, the centers of the coils are spaced apart by 10 … 50 … 100 … 500 … or 1000cm. In some embodiments, the area of each coil is 25 … 625 … 2500 …,500 …, or 250,000cm ² . For the situation when all four coils have the same polarity, the maximum total series capacitance is required. In some embodiments, as shown in fig. 3, this series capacitance is equally distributed among all four coils, balanced on each side of the switching relay. This distributes the capacitance such that the contact voltage at the switch remains minimal. Otherwise, a high "Q" of the coil may result in a voltage on the switch and interconnect that is too high for some configurations, exceeding 10KV.

As described above, additional capacitance (e.g., adding a series capacitor to reduce capacitance) that can be used to maintain the desired resonant frequency is accessed by a polarity switching relay or a separate switch that can be energized when needed. In some embodiments, this capacitance is distributed between the polarity switching relays to minimize terminal voltage and common mode coupling by achieving optimal symmetry.

In some implementations, each capacitive element includes a plurality of capacitors to minimize the voltage across each capacitor to ensure that the voltage capability of the capacitor is not exceeded and to minimize heating due to losses that might otherwise cause a shift in resonant frequency.

In some embodiments, balun is incorporated into the excitation coil as close as possible (see section D below and fig. 3). The balun described below achieves common mode rejection to reduce or eliminate the generation of electric fields and also provides impedance transformation to best match the impedance of the coil assembly to the impedance of the transmission line and power amplifier. In some embodiments, the primary (amplifier side) of the balun has 8 turns and the secondary (coil side) has 4 turns, thus providing a 4 to 1 impedance variation that matches the generator output impedance of, for example, 50 ohms well with the 12 ohm coil impedance at resonance. Other turns ratios may be employed to achieve optimal impedance conversion to other characteristic impedance transmission lines and amplifiers.

Fig. 3 provides an exemplary embodiment of a coil system for use in an excitation assembly. In this figure, the plurality of capacitors are identified by numbers (e.g., C1, C5, C11, C40, etc.; pF (micro-farads)) and their relative positions with respect to coils A, B, C and D (see, e.g., FIG. 4A). Shown with 7: balun with 4 turns ratio (balun transformer ratio matches impedance to 50 ohms, with a ratio of 7:4, where the 50 ohm side is 7 turns and the coil side is 4 turns). The system may be configured or tuned to optimize performance based on the manner in which the coils are utilized. For example, as shown in the exemplary embodiment of fig. 3:

A field: z plane [ ], ++++) capacitors C9 and C10 25,600pf (20,000 in parallel with 5,600 pf);

a field: the X plane (+ - ++ -) capacitors C19 and C20 are 27,235pF (a series combination of 27,000pF and (2) 470pF capacitors is used in parallel);

a field: y-plane (+ ++ -) capacitors C29 and C30 are 6,050pF (2,700 parallel 3,300pF in parallel with a series combination of (2) 100pF capacitors);

general (all fields): capacitors C39 and C40 are 9,000pf ((3) parallel combinations of 3,000pf capacitors); and

the C39 and C40 capacitors (fixed value XY) are 9,000pF (18,000 pF in series with 18,000 pF; can be 9,220pF;8,200 in parallel with 820pF or other combinations; total voltage 660 Vrms).

Other specific capacitance values may be used to provide the desired resonant frequency at different inductance values, which may be produced by different coil structures.

B. Solving exciter field strength near sensor

Typically, the field strength of the actuator used to power the tags is close to that of the actuator in order to create a large volume in which one or more tags may be powered. This field is much greater than the field provided by the one or more tags or transmitters associated with the surgical tool (the tag and transmitter are collectively or individually referred to herein as a "beacon"). Furthermore, since it is preferable that a single excitation assembly device provides both excitation and sensing, the sensing component should be in close proximity to the excitation component. Thus, a magnetic field sensor will typically sense a magnetic field at an exciter frequency that is very large, about 160dB or more greater than the relevant signal (from the beacon).

This problem can be partially solved by means of an electronic filter. However, the rejection capabilities of these filters are limited, they are expensive, and they are physically large. The filter may be active or passive. However, active electronic filters have an inherent noise floor that limits the dynamic range and filtering effectiveness for such very high dynamic range cases, and thus passive filters may be employed in some embodiments.

An alternative (or additional) solution utilizes the coil system described in section a above. In such embodiments, the excitation field picked up by the sensor may be reduced by taking advantage of the vector nature of the magnetic field. In some embodiments, an excitation coil is selected having an orientation that produces only magnetic flux substantially perpendicular to an XY plane containing the sensing coil. In some embodiments, the ferrite core coil, which is also highly oriented in nature, is then aligned with the plane such that magnetic flux orthogonal to the plane is not sensed. This may result in excitation field suppression exceeding 40 dB. In a preferred geometry, greater than 70dB of isolation has been achieved for all sense coils in all three polarity configurations described above. The height and inclination of each witness coil is adjusted to achieve the alignment required to achieve this level of isolation under all three coil polarity conditions. Isolation is typically measured using a vector network analyzer by connecting an excitation coil to port 1 and a specific witness coil to port 2. S is then measured at the reception frequency ₂₁ Is a function of the magnitude and phase of (a). In a preferred embodiment, the selected receiving frequency is 130.2KHz.

Thus, in such embodiments, the system uses one magnetic field direction for excitation, while the other two directions (orthogonal to the excitation direction) are used for sensing. In other embodiments, two orthogonal may be used for stimulation and one orthogonal for sensing. However, it may be preferable to use two orthogonality for sensing to provide a faster estimate of beacon location.

C) Resolving exciter/beacon coupling

In some embodiments, the exciter is a high resonance coil. Because in some embodiments the frequency of the beacon is close to the resonant frequency of the exciter, a portion of the ac magnetic field of the beacon aligned with the exciter coil orientation may induce a current in the exciter, thus producing a magnetic field at the beacon frequency in the exciter coil orientation. This effect distorts the original field of the beacon, making locating the beacon more difficult. In clinically preferred geometries, this distortion masks the true position of the beacon, so that navigation may become difficult or impossible.

This coupling can be reduced by selecting a different beacon frequency that is not too close to the exciter resonance. However, since in certain preferred embodiments the beacon uses a single ferrite core RF coil for both reception and transmission, the available bandwidth is limited.

In contrast, with the exciter configuration described in sections a and B above, no distorted field is detected since the sensing system including the sensing coil is oriented orthogonal to the exciter coil. In other words, the distortion is limited to the direction of the magnetic field being substantially aligned with the excitation coil, which is orthogonal to the sensing system. Therefore, the true position of the beacon is no longer masked by the field distortion generated by the excitation current at the beacon frequency, and thus accurate navigation without artifacts can be achieved.

D) Solving the magnitude of the electric field generated by the system

The actuator and associated circuitry should be designed to minimize the magnitude of the electric field generated by the system. If an electric field is generated, the electric field may capacitively couple into the sensing system and reduce system accuracy. The electric field also interacts with the patient and the environment and is more pronounced than the magnetic field.

In some embodiments, this challenge is addressed by incorporating a balun as close as possible to the excitation coil. Balun may also be used as an impedance transformer that minimizes the electric field by eliminating asymmetric currents with respect to ground. Another consideration is that balun eliminates common mode coupling. In some embodiments, the circuit design and layout should be as symmetrical as possible on the actuator side of the balun to maintain balance.

In addition to reducing the effects of the electric field, the transformer also allows the use of off-the-shelf 50 ohm coaxial transmission lines without mismatch. This allows the voltage and current of the transmission line to be scaled to optimally transfer power to the exciter assembly with optimal efficiency and minimal, most flexible coaxial cable.

E) Identifying and managing the location of multiple beacons

In some embodiments, one or more beacons (e.g., tags, transmitters associated with one or more surgical devices, or other objects whose positioning, location, relative position, or other spatial information is desired) are employed. In some embodiments, each different beacon generates a unique frequency, frequency spectrum, or otherwise distinguishable signal. In some such embodiments, a search algorithm is employed to identify spatial information of one or more beacons. In some implementations, by cycling the exciter on different planes, the optimal exciter polarity and power level is identified for each beacon (e.g., taking into account any relative orientation of the beacon with respect to the exciter). Based on this information, an optimal actuator pattern is calculated to maximize the quality of the procedure and the accuracy of the information communicated to the user (e.g., treating physician). In some such embodiments, the first best mode is utilized to provide spatial information about the first tag and the first portion of the procedure is performed. Next, spatial information about the second tag is provided using a second best mode (which may be the same or different), and a second portion of the program is performed. Additional tags may be further cycled. Alternatively, during the process of providing near real-time optimal spatial information for multiple beacons, the exciter mode (polarity and power) may cycle between multiple different optimal modes. In some such embodiments, a fast switching of coil polarity in the transmitter is employed to simultaneously or near simultaneously power two or more beacons.

F) Overview of exemplary System and device Components

In some implementations, the systems, devices, components, and methods may be used in electromagnetic navigation systems that power remote tag devices with sinusoidal magnetic fields (see, e.g., U.S. patent No. 9,730,764 and U.S. application nos. 15/281,862 and 15/674,455, the entire contents of which are incorporated herein by reference). In some embodiments, the tag is wireless and desirably of minimal size. In some embodiments, the tag generates its own time-varying magnetic field at one or more sideband frequencies when energized. The shape of the magnetic field is approximately that of a magnetic dipole located at the tag. By monitoring the magnetic field at several locations using a receiving antenna coil (also known as a sensing coil or witness station), the location of the tag can be identified. In some embodiments, the systems, devices, assemblies, and methods further comprise an electrosurgical tool. In some embodiments, the electrosurgical tool or a component attached to or physically adjacent to the tool includes two or more position transmitters that also generate a magnetic field similar to a magnetic dipole. In some embodiments, the transmitter is driven with two different frequency signals that are also different from the exciter frequency and the tag response frequency. In certain embodiments, the position transmitter is wired to the signal supply.

In some embodiments, a single excitation assembly (e.g., as shown in fig. 4A) is employed to generate a signal that interacts with the tag and a position transmitter in an attachment component associated with the electrosurgical tool. In some embodiments, the excitation assembly is housed in a single thin assembly. In some embodiments, the assembly including the exciter further includes a sensor (e.g., a receive antenna/sense/witness station coil). In some embodiments, the incentive assembly is configured to be deployed beneath a patient undergoing a medical procedure. An exemplary procedure configuration is shown in fig. 1, wherein a patient 90 is located on a surface 95 (e.g., a mattress or operating table). The surface 95 is held by a surface frame 97. Patient 90 has a lesion (e.g., tumor) 110 and an implant label 100 positioned near, on, or in the tumor. The excitation assembly 250 is located below the patient and below the surface (e.g., on the surface frame 97) and generates an electromagnetic field (not shown) in an operating field above the patient in an area surrounding the patient that encloses the location of the tag 100 and the medical device 20 (e.g., surgical device).

Fig. 2 illustrates an exemplary electrocautery surgical device (e.g., BOVIE) that may be used in some embodiments of the present invention. The apparatus 20 comprises: a tip 25 providing an operative surface for treating tissue; two embedded position transmitters 70 that allow the system to sense the location and position of the device 20; and a display unit 40 that provides visual information to a user (e.g., a surgeon) regarding the location of the tag within the patient.

In some embodiments, the excitation component is configured to provide enhanced detection of remote objects (e.g., tags and surgical devices) under many different settings that would otherwise complicate real-time assessment of location, position, and distance assessment, particularly such factors.

In some embodiments, the systems and methods include a plurality of components. In some embodiments, the first component comprises one or more tags (used interchangeably with the term "tag") whose location, position, distance or other property is to be assessed. In some embodiments, the tag is configured to be positioned within the subject at a surgical or other clinically relevant location to mark a target area within the subject. In some embodiments, the second component includes a remote activation device (e.g., an excitation assembly) that generates a magnetic field. In some embodiments, the second component is located in a device positioned near (e.g., below) the subject containing the one or more tags. In some embodiments, the third component includes a plurality of witness stations configured to receive signals generated by the one or more tags when exposed to the magnetic field generated by the second component. In some embodiments, the second and third components are physically housed in the same device (e.g., as shown in fig. 4A). In some embodiments, the fourth component comprises a medical device position transmitter. The fourth component may be integrated into the medical device or attached or otherwise associated with an attachment component (e.g., sheath). The fourth component includes one or more position transmitters (e.g., antennas or other types of transmitters that transmit signals) that generate signals via an electrical feed line or when exposed to a magnetic field generated by the second component, the signals being detectable by the third component. In some embodiments, the fifth component includes a computing device that includes a processor that receives information from the witness station of the third component and generates information regarding the relative location, distance, or other characteristic of the tag, medical device, and witness station. In some implementations, the fifth component includes a display that displays such generated information to a user of the system.

In some embodiments, the first component is a single label. In some embodiments, it is two or more tags (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.). In some embodiments, where more than one tag is used, the tags are of the same type, while in other embodiments they are of different types.

In some embodiments, the tag includes a ferrite core coil antenna (e.g., resonating at 100-200 kHz) coupled to an Integrated Circuit (IC), the ferrite core coil antenna being powered by an AC magnetic field at resonance. In some embodiments, the core is housed in an outer shell (e.g., a cylindrical glass or plastic shell). In some embodiments, the excitation antenna is driven by a conventional oscillator and power amplifier at a level sufficient to power the tag. In some embodiments, the implanted tag Amplitude Modulates (AM) the Continuous Wave (CW) carrier power from the exciter, thus transmitting sidebands at frequencies defined by the values programmed into the tag's counter. In some embodiments, these sidebands and the stronger CW carrier are ultimately detected by the third component.

In some embodiments, the tag includes a self-resonating object (e.g., a small ferrite core with a wound inductor). The wound inductor has an inter-winding capacitance that, in combination with the inductance, creates a high frequency resonant circuit. In some embodiments, the tag includes a resonating object (e.g., a self-resonating object is equipped with a chip capacitor to produce resonance at a specified frequency). In some embodiments, the tag includes a resonant or self-resonating object with a diode. The diode and LC circuit generate subharmonic frequencies when immersed in a magnetic field of sufficient strength (the applied voltage exceeds the bandgap potential of the diode). In some embodiments, the tag includes a resonating object or a self-resonating object having an active modulator (e.g., an integrated circuit amplitude modulates a resonating circuit). In some embodiments, detection proceeds similarly to Full Duplex (FDX) Radio Frequency Identification (RFID), except that the modulation mode is a simple subharmonic rather than a coded binary mode; in some embodiments, detection occurs after excitation, similar to Half Duplex (HDX) mode of operation.

In some embodiments, the tag is configured for single use. In some such embodiments, the activation tag may be deactivated or deactivated (e.g., like an EAS tag). This is particularly useful where multiple tags are used in the procedure of closing individual tags to simplify detection of other tags (e.g., to avoid or reduce interference between multiple tags). In some implementations, a burst of energy from an external device is used to deactivate or deactivate the activation tag. In other embodiments, the tag has an internal control that turns the tag on or off (e.g., the tag temporarily or permanently stops "talking") upon receiving instructions from an external device.

In some embodiments, the label has an outer length, width, and depth, wherein the length is 30mm or less (e.g., 20mm or less, 0.5mm or less, 10mm or less, 9mm or less, 3mm or less, etc.), the width is 5mm or less (e.g., 4mm or less, 3mm or less, 2mm or less, 1mm or less, 0.5mm or less, etc.), and the depth is 5mm or less (e.g., 4mm or less, 1mm or less, etc.).

In some embodiments, the tag is housed in a housing. In some embodiments, no housing is employed. In some embodiments, the housing comprises a biocompatible material. In some embodiments, the housing provides a liquid and/or gas resistant barrier that separates the signal source from the exterior of the housing. In some embodiments, the housing is small, allowing the tag to be applied through a needle, cannula, endoscope, catheter, or other medical device. In some such embodiments, the housing has an outer length, a width, and a depth, wherein the length is 30mm or less (e.g., 20mm or less,) 10mm or less, # 9mm or less, # 8mm or less, # 5mm or less, # 3mm or less, # and the like), the width is 5mm or less (e.g., 4mm or less, # 3mm or less, # 2mm or less, # 1mm or less, # 0.5mm or less, # and the like), and the depth is 5mm or less (e.g., 4mm or less, # 1mm or less, # 0.5mm or less, # 2mm or less, # and the like). The housing may be of any desired shape. In some embodiments, the housing is cylindrical along the length axis. In some embodiments, the shell is shaped like a rice grain (e.g., a cylinder with rounded ends). In some embodiments, the housing is shaped like a pillar (e.g., a cylinder with flat ends). In some embodiments, the housing is polygonal along the length axis (e.g., triangular, square, rectangular, trapezoidal, pentagonal, etc. in cross-section). In some embodiments, the housing has struts or other fasteners to hold the tag in place, avoiding migration in tissue. These struts may be deployed when placed in tissue. In some embodiments, the fastener may be a biocompatible material that binds with surrounding tissue.

In some embodiments, the housing is a single uniform component that is synthesized around the interior components of the tag. In other embodiments, the housing is made of two or more separate segments that are sealed together after introduction of the internal components of the tag. In some embodiments, the label is fully or partially covered in a coating. In some embodiments, the coating comprises a biocompatible material (e.g., parylene-C, etc.).

In some embodiments, the tag does not include any power source. For example, in some embodiments, a signal is generated from a signal source in response to a magnetic field (i.e., electromagnetic induction) as an activation event.

In some embodiments, the tag includes a Radio Frequency Identification (RFID) chip (e.g., in a housing). In some embodiments, the RFID chip includes a radio frequency electromagnetic field coil that modulates an external magnetic field to transmit an encoded identification number and/or other encoded information when interrogated by a reader device. In some embodiments, the RFID chip collects energy from the EM field generated by the second component (or other device) and then acts as a passive transponder to emit microwaves or UHF radio waves. In some embodiments, the RFID chip is read-only. In other embodiments, it is read/write. The techniques are not limited by the nature of the information provided by the RFID chip. In some embodiments, the information includes a serial number, lot or batch number, time information (e.g., date of manufacture; date of surgery; etc.); patient specific information (e.g., name, family history, medication, allergies, risk factors, type of surgery, gender, age, etc.); program specific information; etc. The technique is not limited by the frequency of use. In some embodiments, the RFID frequency is in the 120-150kHz band (e.g., 134 kHz), 13.56MHz band, 433MHz band, 865-868MHz band, 902-928MHz band, 2450-5800MHz band, and so forth. In some embodiments, the RFID chip is combined with browser-based software to increase its efficiency. In some embodiments, the software allows different teams or specific hospital staff, nurses and patients to view real-time data relating to labels, procedures or personnel. In some embodiments, the real-time data is stored and archived to take advantage of historical reporting functions and to demonstrate compliance with various industry regulations. In some embodiments, the RFID chip reports sensor data (e.g., temperature, motion, etc.). In some embodiments, the RFID chip contains or collects information that is read at a later time (e.g., after surgery). In some embodiments, the information is reviewed during surgery. For example, a message may be provided to the surgeon (e.g., "chip just to the left of the tumor") to help guide the surgeon (e.g., optimize tumor removal with the appropriate margin).

In some embodiments, the tag consists of or consists essentially of a signal source and a housing or a signal source, a housing and an RFID chip. In some implementations, the tag transmits an ultrasonic signal (e.g., grayscale, spectral, or color doppler) (e.g., via a chip) such that the signal is detectable by an ultrasonic probe or a handheld doppler unit.

In some embodiments, the tag is heated during surgery (e.g., by exposure to an external energy source). In some such embodiments, heating may be used to assist in coagulation or pre-coagulation of tissue or to provide thermal therapy (see, e.g., U.S. patent publication No.2008/0213382, which is incorporated herein by reference in its entirety). Heating may also be used to increase the efficiency of radiation therapy.

In some embodiments, the second component provides a remote activation device (e.g., the excitation assembly shown in fig. 4A) having one or more excitation coils. In some embodiments, the excitation coil is disposed in a patch or pad placed on the patient or operating table, but it may be located at any desired location within the functional distance of the tag. In some embodiments, the remote activation device provides an AC magnetic field originating from one or more excitation antennas. In some embodiments, where the system is used to locate a breast tumor, the patch is wrapped around or otherwise placed in proximity to the treated breast. Similar methods can be used for other target areas of the body. In some embodiments, a pad containing an excitation coil is placed under the patient. In such embodiments, a large coil or multiple coils are employed. The excitation coil may comprise or consist of several turns of a planar conductor patterned on a dielectric substrate, or may comprise or consist of magnetic wire wound on a suitable mandrel; the coil is powered by an external frequency source and a magnetic field emanating from the coil penetrates the patient's body to excite the tag, the emission of which is detected by the detection component.

In some embodiments, the one or more excitation coils are housed in a band placed around the subject or a portion of the subject. In some embodiments, the external excitation coil may also be used in other aspects of patient care, such as for radiotherapy or as a ground current return pad for use in electrosurgery. In some implementations, the remote activation device emits light (e.g., laser light). In some embodiments, the remote activation device is configured to be disposable (e.g., disposable).

In some embodiments, the remote activation device is activated with an unmodulated constant frequency (i.e., the activation signal has a constant amplitude and frequency). In some embodiments, the remote activation device employs an unmodulated frequency sweep (i.e., the activation signal has a constant amplitude and frequency sweep between two endpoints). Such devices may be used with resonant tags such that when the transmit frequency coincides with the resonant frequency of the tag, a detectable change in the amplitude of the activation signal occurs. In some embodiments, the remote activation device employs a pulse frequency (i.e., the activation signal includes a brief excitation pulse at a periodic frequency, which may include two closely related frequencies, the sum or difference of which is the response frequency of the tag). Pulse activation produces a post-pulse sinusoidal decay signal. The tag changes the characteristics of the attenuated signal in amplitude or time.

In some embodiments, the remote activation device comprises a hand-held component. In some embodiments, the hand-held component is lightweight to allow a surgeon to hold and manipulate the component (e.g., 5kg or less, 4kg or less, 3kg or less, 2kg or less, 1kg or less, 0.5kg or less, 0.25kg or less, or any range therebetween, e.g., 0.5 to 5kg, 1 to 4kg, etc.) during a surgical procedure. In some embodiments, the hand-held member is shaped like a stick having a proximal end held by a physician and a distal end directed toward the subject or tissue being treated with the tag. In some embodiments, the handheld component is shaped like an otoscope, with its distal end terminating at an angle (e.g., right angle) to the body of the component. In some embodiments, the remote activation device includes an antenna that generates a magnetic field. In some embodiments, the remote activation device has only a single antenna (i.e., is single-base). In some embodiments, the remote activation device has only two antennas (i.e., is bistatic).

In some embodiments, the magnetic field of the remote activation device (e.g., the excitation assembly shown in fig. 4A) is controlled by a processor running a computer program. In some embodiments, the remote activation device includes a display or user interface that allows a user to control the remote activation device and/or monitor its functions in use. In some implementations, the remote activation device provides visual, audio, numeric, symbolic (e.g., arrow), text, or other output that assists the user in locating the distance of the tag or identification tag from the remote activation device or the direction relative to the remote activation device.

In some embodiments, the plurality of witness coils of the third component collectively provide a plurality of antennas at a plurality of defined positions relative to the tag and are configured to receive signals generated by one or more tags when exposed to the magnetic field generated by the second component.

In some implementations, each witness coil feeds a receiver channel that is Time Division Multiplexed (TDM) to reduce receiver complexity. A fixed witness station in a defined position relative to the tag and each other (e.g., along the patient line) includes one or more (e.g., one to three) witness coils arranged in a partially orthogonal manner to sense various components of the AC magnetic field from the tag. In some implementations, one or more or all of these witness coils in the witness station are also TDM into the receiver channel, reducing complexity and cross-talk between antennas.

In some embodiments, the witness coil includes or consists of a ferrite-loaded cylindrical coil antenna tuned (e.g., with one or more capacitors in parallel) to resonate at the frequency (e.g., 100-200 kHz) of the exciter (e.g., tag or transmitter). Typical dimensions for witness coils are 3-5mm in diameter and 8-12mm in length, although smaller and larger dimensions may be used.

In some embodiments, the witness station is disposed below the patient (e.g., in a pad, garment, or other device located below the patient). In some embodiments, the witness station is integrated into an operating table or imaging device into which the patient may be placed during the medical procedure. In some embodiments, the witness station is placed on the floor, wall, or ceiling of the operating room or in a medical transportation vehicle. In some embodiments, the witness station is integrated with or attached to a medical device used in a medical procedure.

In some embodiments, the fourth component is provided with a medical device position transmitter (see fig. 9-12) in the attachment component to allow the system to determine the location, position, distance, or other characteristic of the medical device relative to the one or more tags. In some embodiments, one or more medical device position transmitters are integrated into the medical device or attachment component. In other embodiments, they may be attached to a medical device. In some such embodiments, the position transmitter is disposed in an attachment member (e.g., a sleeve) that slides over a portion of the medical device. The position transmitter may operate as a tag and/or comprise the same material as the tag, but be positioned on or near the medical device rather than within the tissue. For example, in some embodiments, the transmitter includes a coil that is energized with carriers and/or sidebands, thereby enabling the transmitter to transmit a signal as if it were a tag. In other embodiments, the position transmitter is wired to a power source and a signal source.

In some implementations, locating the position transmitter is geometrically accomplished by measuring quasi-simultaneous power detected from the transmitter at multiple witness stations (e.g., four or more stations) and using power differences to perform vector mathematical operations that explicitly determine the position of the transmitter. This process can be simplified by performing a preliminary calibration using known tags at known locations prior to the procedure.

Vectors describing the position of the position transmitter are used to provide visual guidance to the surgeon regarding the spatial relationship of the medical device (e.g., particularly its tip) to the implanted label or (e.g., under computational guidance) to the lesion boundary. Vectors are provided using a plurality of position transmitters on an attachment member attached to a medical device to determine a principal axis of the device using the same vector mathematical operation. In the case of more complex medical devices, such as robotic surgical systems (e.g., da vinci surgical systems), multiple position transmitters located at multiple different locations of the device are employed to provide positioning, orientation, and other positional information of multiple components (e.g., arms) of the device. In some embodiments, the position emitter also serves as a detector (e.g., witness stations are provided on the medical device).

In some embodiments, the fifth component provides one or more computing systems that include one or more computer processors and appropriate software to analyze, calculate, and display tag and transmitter location information (see section 210 in fig. 4A). In some embodiments, the display provides a graphical representation of the label, patient, and/or medical device on the monitor. In other embodiments, the display provides directional information for moving or positioning the medical device. In some embodiments, the system automatically (e.g., robotically) controls the medical device or one or more functions thereof. In some embodiments, the display integrates the tag and/or medical device information with previously acquired or concurrently acquired medical images (e.g., CT, MRI, ultrasound, or other imaging modalities) of the patient or target tissue. For example, in some embodiments, an image indicative of one or more tags is fused with an image of a tissue or body region of a subject obtained from an imaging device. In some embodiments, the information is analyzed in real-time. In some embodiments, the information is analyzed at one or more discrete points in time.

In some embodiments, the fifth component provides command and control functions for a user of the system. In some embodiments, the fifth component has information stored thereon that helps guide the information displayed on the attachment component. For example, the information may include data regarding the type of medical device to which the attachment member is attached, or data regarding which tip or cutting tool a particular medical device is using. In this regard, the precise location of the cutting tip of the medical device and its relationship to the tag (e.g., distance to the tag) is communicated to the surgeon (e.g., to obtain a very precise indication of the cut tissue). Such information is, for example, in some embodiments manually entered into the control unit or attachment component by a user, or automatically found (e.g., by a bar code or other indicator) when the detection component is attached to a particular medical device.

The system may be used with a variety of medical devices and procedures. In some embodiments, the surgical device comprises an electrosurgical device that is turned on and off by a user, wherein the control unit that is part of the fifth component allows the remote activation device to generate a magnetic field when the electrosurgical device is turned off and prevents the remote activation device from generating a magnetic field when the electrosurgical device is turned on (e.g., ensuring that the surgical device and the detection system do not interfere with each other). In other embodiments, the surgical device includes a power cord, wherein the AC current clamp is attached to the power cord, wherein the AC current clamp is electrically or wirelessly connected to the control unit, wherein the AC current clamp senses when the electrosurgical device is turned on or off and reports this to the control unit (e.g., so that the control unit can ensure that magnetic fields from the surgical device and the remote activation device will not be activated at the same time).

In certain embodiments, the surgical device comprises an electrocautery device, a laser cutting device, a plasma cutting device, or a metal cutting device (e.g., a surgical device manufactured by BOVIE MEDICAL). Other examples of medical devices that may be used in embodiments of the system are found, for example, in the following U.S. patents: 9,144,453;9,095,333;9,060,765;8,998,899;8,979,834;8,802,022;8,795,272;8,795,265;8,728,076;8,696,663;8,647,342;8,628,524;8,409,190;8,377,388;8,226,640;8,114,181;8,100,897;8,057,468;8,012,154;7,993,335;7,871,423;7,632,270;6,361,532; the foregoing are incorporated by reference herein in their entirety, and in particular with respect to the handheld medical devices disclosed therein.

In some embodiments, the attachment member has a display member thereon or attached thereto for guiding the surgeon to find one or more labels. In some embodiments, the display component provides: i) A spatial orientation indicator (e.g., visual, audible, etc.), and/or ii) a distance indicator to the tag (e.g., visual, audible, etc.). In some embodiments, the display part includes: a first display for presenting distance information (e.g., visual, audible, light, color, vibration, tactile, etc.) to the tag; a second display for presenting a vertical axis orientation, such as a preset preferred angle (e.g., visual, audible, light, color, vibration, tactile, etc. display) proximate to a tag within the patient; and/or a third display for presenting a horizontal orientation (e.g., left to right information, thus centering the surgical device when approaching the tag). In some embodiments, the display component includes multiple displays (e.g., visual, audible, sensory, etc.) that allow the correct pitch and yaw axes to be employed (to minimize non-target tissue damage) and/or also includes a display that provides distance information to the tag. In certain embodiments, the medical device is moved around the patient's body to orient the emitter and display component prior to the surgical procedure. In certain embodiments, a series of lights and/or sounds are provided on a display component that guides the surgeon (e.g., the surgeon tries to keep the lights in the center of the "X" series of lights, and/or the volume of the alarm sounds is kept off or as low as possible).

The tag is not limited to placement within a particular body area, body part, organ or tissue. For example, in some embodiments, the tag is placed in the head, neck, chest, abdomen, pelvis, upper limb, or lower limb area of the body. In some embodiments, the tag is placed within an organ system, such as the skeletal system, the muscular system, the cardiovascular system, the digestive system, the endocrine system, the cortex system, the urinary system, the lymphatic system, the immune system, the respiratory system, the nervous system, or the reproductive system. In some embodiments, the tag is placed within the organ. Such organs may include heart, lung, blood vessels, ligaments, tendons, salivary glands, esophagus, stomach, liver, gall bladder, pancreas, intestine, rectum, anus, hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid gland, adrenal gland, skin, hair, fat, nails, kidneys, ureters, urinary tract, pharynx, larynx, bronchi, diaphragm, brain, spinal cord, peripheral nervous system, ovaries, fallopian tubes, uterus, vagina, breast, testes, vas deferens, seminal vesicles, and prostate. In some embodiments, the tag is placed within tissue, such as connective tissue, muscle, nerve, and epithelial tissue. Such tissues may include myocardial tissue, skeletal muscle tissue, smooth muscle tissue, loose connective tissue, dense connective tissue, reticular connective tissue, adipose tissue, cartilage, bone, blood, fibrous connective tissue, elastic connective tissue, lymph node connective tissue, areola connective tissue, single-layered squamous epithelium, single-layered cubic epithelium, single-layered columnar epithelium, multi-layered epithelium, pseudo-multi-layered epithelium, and transitional epithelium.

In some embodiments, the tissue region in which the tag is located includes a lesion. In some embodiments, the lesion is a tumor or tissue region identified as being at risk of forming a tumor. In some embodiments, the lesion is a fibrotic tissue. In some embodiments, the lesion is an inflamed or infected area. In some embodiments, a tag is placed within the lumen to detect the function or other process of the organ or to provide positioning information. For example, the tag may be swallowed or placed into a hollow organ via endoscopic techniques. In some embodiments, the tissue region is healthy tissue.

In certain embodiments, the tag is placed within a solid tumor. Examples of solid tumors in which the tag may be placed include carcinomas, lymphomas and sarcomas, including but not limited to, abnormal basal cell carcinoma, acinar carcinoma, adenoid cystic carcinoma, adenoid/pseudoadenosquamous cell carcinoma, adnexal tumor, adrenocortical adenoma, adrenocortical carcinoma, basal cell carcinoma, basal squamous cell carcinoma, carcinoid, hepatobiliary tract type liver cancer, scar basal cell carcinoma, clear cell adenocarcinoma, clear cell squamous cell carcinoma, combined small cell carcinoma, acne carcinoma, complex epithelium carcinoma, cylindrical tumor, cystic carcinoma, cystic basal cell carcinoma, cystic tumor, ductal carcinoma, endometrial tumor, epithelial tumor, extramammary paget's disease, familial adenomatous polyposis, pink fibrous epithelium tumor, gastrinoma, glucagon tumor, graz tumor, hepatocellular adenoma, sweat gland cyst tumor, hepatoma, cystic carcinoma a helcell, permeable basal cell carcinoma, insulinoma, intraepidermal squamous cell carcinoma, invasive lobular carcinoma, introverted papilloma, keratoacanthoma, kras tumor, klukenberg tumor, large cell keratinized squamous cell carcinoma, large cell non-keratinized squamous cell carcinoma, leathery stomach, liposarcoma, lobular carcinoma, lymphoepithelial carcinoma, ductal carcinoma of the breast, medullary carcinoma of the breast, medullary carcinoma of the thyroid, small nodular basal cell carcinoma, scleroderma-like basal cell carcinoma, moss basal cell carcinoma, mucous cyst adenocarcinoma, mucous epidermoid carcinoma, multiple endocrinopathy, neuroendocrine tumor, nodular basal cell carcinoma, eosinophiloma, osteosarcoma, ovarian serous cyst adenoma, paget's disease of the breast, ductal carcinoma of the pancreas, pancreatic serous cyst adenoma, papillary carcinoma, papillary sweat gland adenoma, papillary serous cyst adenoma, papillary squamous cell carcinoma, pigment basal cell carcinoma, polypoid basal cell carcinoma, hole-like basal cell carcinoma, prolactinoma, peritoneal pseudomyxoma, renal cell carcinoma, renal eosinophiloma, aggressive ulcers, serous carcinoma, serous cyst adenoma, stomach-ring cell carcinoma, pancreatic-ring cell squamous cell carcinoma, skin accessory tumors, small cell carcinoma, small cell keratosis squamous cell carcinoma, somatostatin tumor, spindle cell squamous cell carcinoma, lung squamous carcinoma, thyroid squamous cell carcinoma, epidermal basal cell carcinoma, epidermal multicenter basal cell carcinoma, papillary sweat duct cyst adenoma, sweat duct tumor, thymoma, transitional cell carcinoma, warty squamous cell carcinoma, vasoactive intestinal peptide tumor and adenolymphoma.

In some embodiments, placing the tag comprises the steps of: inserting an introduction device into the subject, and introducing a tag into the subject through the introduction device. In some embodiments, the introduction device is a needle, cannula, or endoscope. In some embodiments, the tag is forced through the introduction device (e.g., via physical force, pressure, or any other suitable technique) and released into the subject at the distal end of the introduction device. After placement of the tag, the introduction device is withdrawn, leaving the tag in the desired location within the subject. In some embodiments, the introduction of the tag is guided by imaging techniques.

In some embodiments, a plurality of tags are placed into a subject. The tags may be of the same type or may be different (e.g., signal types are different). The tags may be placed close to each other or at a remote location. In some embodiments, multiple tags are used to triangulate a location intended for medical intervention.

In some embodiments, the tag also serves as a fiducial for radiation therapy (or other targeted therapy). The position of the tag is recognized by an external reader and used, for example, to place a laser on the skin surface where the chip is located. This eliminates the need to use X-rays, CT or fluoroscopy to view the fiducial points. This also reduces or eliminates the need to place skin marks (e.g., tattoos) on the patient. This also helps in respiratory compensation as the fiducial point moves up and down with the lung or abdominal tumor. Thus, real-time irradiation is only possible when the tumor is in the correct position, and damage to background tissue is reduced (e.g., avoiding burning vertical streaks in the patient as the tumor moves up and down). The use of fiducial points as a guide treatment (e.g., radiation treatment) also enhances triangulation because depth information (based on signal strength) aids in tumor localization to minimize collateral damage.

In some embodiments, provided herein are systems and methods employing one or more or all of the following: a) A tag (e.g., including an antenna; for example, a coil antenna; for example, ferrite core coil antennas; for example, resonating at 100-200 kHz; for example, coupled to an integrated circuit); b) A remote activation device that generates a magnetic field within the tag region; and c) a plurality of witness stations, each witness station comprising an antenna configured to detect information generated by the tag or a change in magnetic field generated by a remote activation device caused by the tag. In some embodiments, the tag emits sidebands at defined frequencies when activated by a magnetic field, and the witness station detects such sidebands. In some embodiments, the tag transmits sidebands at frequencies defined by the values in the counter programmed into the tag.

In some embodiments, the remote activation device includes an excitation coil that is powered, for example, by a generator electrically connected to the remote activation device. In some embodiments, the remote activation device includes a pad configured to be placed near (e.g., below, above, beside) the patient with a tag embedded within the patient. In some embodiments, the pad further comprises a witness station.

Any number of other tag designs may be employed. In some embodiments, the tag comprises or consists of an iron pellet or an iron particle. When a ferrous object is introduced into the magnetic field, the object may create irregularities in the alternating magnetic field that may be detected by an induction coil housed within the witness station, thereby creating a phase and amplitude offset relative to zero. When the ferrous object is physically equidistant from the two induction coils, a zero value will resume.

In some embodiments, the tag includes a self-resonating object (e.g., a small ferrite core with a wound inductor). The wound inductor has an inter-winding capacitance that, in combination with the inductance, creates a high frequency resonant circuit. For example, detection is performed using the method described above for iron pellets or, for example, using a Grid Dip Oscillator (GDO). The GDO has a resonant circuit that radiates an electromagnetic field. When approaching self-resonating objects of the same frequency, the power transfer from the GDO to the self-resonating object may cause a detectable change in the GDO power. In some embodiments, the tag includes a resonating object (e.g., a self-resonating object is equipped with a chip capacitor to produce resonance at a specified frequency). In some embodiments, the tag includes a resonant or self-resonating object with a diode. The diode, in combination with the LC circuit, generates subharmonic frequencies when immersed in a magnetic field of sufficient strength (the applied voltage exceeds the bandgap potential of the diode). In some embodiments, the tag includes a resonating object or a self-resonating object having an active modulator (e.g., an integrated circuit amplitude modulates a resonating circuit). Detection is similar to Full Duplex (FDX) Radio Frequency Identification (RFID) except that the modulation mode is a simple subharmonic mode rather than a coded binary mode.

In some implementations, each witness antenna includes or consists of a ferrite-loaded cylindrical coil antenna tuned (e.g., with one or more capacitors in parallel) to resonate at the frequency (e.g., typically 100-200 kHz) of an exciter (e.g., tag or transmitter). Typical dimensions for witness antennas are 3-5mm in diameter and 8-12mm in length, although smaller and larger antennas may be used. In some embodiments, the ferrite core of the witness station antenna is 0.25 x 1 inch in size and comprises 75-80 turns of 10/46 (10 # 46) strands that provide 0.157mH (q=53) (75 turns).

In some embodiments, each witness coil is symmetrically wound on the ferrite core and connected to the secondary of the small balun transformer by two series capacitances (one for each line in the coil). The total series capacitance is selected to resonate in conjunction with the inductance of the coil, and the turns ratio of the balun transformer may be selected to match the resonant coil/capacitor circuit to the real impedance of the transmission line (typically 50 ohms). The real impedance of the resonant coil/capacitor circuit is typically 10 to 25 ohms, but can range from just a few ohms to greater than 50 ohms and can be suitably matched by appropriate selection of the primary and secondary turns of the balun transformer. In addition to acting as an impedance transformer, balun also minimizes any electric field generation/susceptibility from the witness coil assembly; alternatively, it may be considered to eliminate the common mode effect.

In some embodiments, each witness station contains 1-3 witness antennas oriented orthogonal to each other and is also arranged to have minimal crosstalk (i.e., interfere with each other). The means for accommodating witness stations also includes one or more receiver channels for collecting information obtained by the antennas of the witness stations. In some embodiments, the receiver includes or consists of one or more channels, each fed by one or more witness antennas (via a multiplexing switch).

The component (e.g., attachment component) that includes the position transmitter may also include a display to assist the user in guiding the medical device to the tag during the surgical procedure. In some such embodiments, a visual or audio display is provided on or associated with the medical device that receives the location information about the tag from the computer system. The display may be one or more direction indicators, such as LEDs, that indicate direction and/or distance to the tag. Color changes may be employed to indicate locations that are "on the target" and "off the target". In some embodiments, a display includes: a first display for presenting distance information (e.g., visual, audible, light, color, vibration, tactile, etc.) to the tag; a second display for presenting a vertical axis orientation, such as a preset preferred angle (e.g., visual, audible, light, color, vibration, tactile, etc. display) proximate to a tag within the patient; and/or a third display for presenting a horizontal orientation (e.g., left to right information, thus centering the surgical device when approaching the tag). In some embodiments, the display includes multiple displays (e.g., visual, audible, sensory, etc.) that allow the correct pitch and yaw axes to be employed (to minimize non-target tissue damage) and/or also includes a display that provides distance information to the tag. In certain embodiments, a series of lights and/or sounds are provided on a display that guides the surgeon (e.g., the surgeon tries to keep the lights in the center of the "X" series of lights, and/or the volume of the alarm sounds is kept off or as low as possible).

The technique is not limited by the tag placement mode and a wide variety of placement techniques are contemplated, including but not limited to open surgery, laparoscopy, endoscopy, via intravascular catheters, and the like. The tag may be placed by any suitable means including, but not limited to, a syringe, endoscope, bronchoscope, extended bronchoscope, laparoscope, thoracoscope, and the like. Exemplary schemes are provided below.

Patients previously identified as having a breast tumor are sent to a medical facility. The patient is initially sent to the radiology department. The radiologist examines prior imaging information identifying the target tumor. Topical anesthetics, typically lidocaine or derivatives, are administered to a subject using percutaneous introduction. The subject is placed in an imaging device, typically an ultrasound, conventional mammography or stereotactic unit. The location of the tumor is determined. A needle (typically 6-20 gauge) is inserted into or immediately adjacent to the tumor, and a biopsy needle is placed through the needle and used to obtain a sample using a variety of methods (aspiration, mechanical cutting, freezing to fix the position of the tissue, and then mechanical cutting). After the specimen is obtained and sent for pathological examination, a 6-20 gauge label delivery needle is inserted into the coaxial needle to reach the tissue with the distal open end at the lesion. The tag is inserted into the proximal end of the delivery needle and delivered through the opening at the distal end of the needle into the tissue by the plunger. Also, the tag may already be pre-positioned at the distal end of the delivery needle. The proper location of the tag is confirmed via imaging. The delivery needle is withdrawn, leaving the tag in the breast tissue.

This type of procedure can be performed in a similar manner in almost any body space, organ or pathological tissue in the hope of locating that tissue or space for further any kind of diagnosis or treatment. Areas of particular interest include, but are not limited to, the following organs and disease processes occurring within them: brain, skull, head and neck, thoracic cavity, lung, heart, blood vessels, gastrointestinal structures, liver, spleen, pancreas, kidney, retroperitoneal, lymph nodes, pelvis, bladder, genitourinary system, uterus, ovary and nerves.

In some embodiments, during surgery, the patient is placed on an operating table and the surgical field is exposed and sterilized. The surgeon is provided with imaging information showing the location of the target tissue (e.g., tumor) and the tag. An incision is made at the location of the entry point for the needle. The remote activation device is placed in proximity to the tissue to activate the tag. A detection component (e.g., as shown in fig. 4A) that includes a witness station detects the signal from the tag and allows the surgeon to direct the direction of the medical device toward the tumor. Once the tumor is located, the surgeon removes the appropriate tissue and optionally removes the tag.

In some embodiments, the system may be used intraoperatively, with the tag placed on or in the body as a fiducial point. Electromagnetic fields are used to determine the relative position of the tag and any surgical instrument. This information is communicated to the physician in real time using a variety of methods including, but not limited to, vision (computer screen, direction and depth indicators using a variety of methods, tactile feedback, audio feedback, holograms, etc.), and the position of the instrument displayed on any medical image in 2D or 3D such as a CT, MRI, or PET scan. This data may be used to guide the physician during surgery or as a training method so that the physician may perform virtual surgery. Such a system may be integrated into or provide an alternative to existing surgical systems, such as the steath system (Medtronic) for applications such as neurosurgery.

In some embodiments, information about the location of one or more tags or the surgical path or route to the tag is communicated to a surgeon or other user in a manner that includes one or more augmented reality or virtual reality components. For example, in some embodiments, a surgeon wears or accesses a virtual reality device (e.g., goggles, glasses, helmets, etc.) that shows a partial or complete virtual image of a patient or surgical field of view. The tag location information collected and calculated by the systems described herein is presented to the surgeon through one or more visual components to help accurately target one or more tags. For example, an organization containing tags may be presented with virtual images of the locations of the tags shown. Likewise, in some embodiments, the surgical path visually appears as, for example, a colored line to follow. In some embodiments employing augmented reality features, the display presents a graphical or video capture of the patient that represents what the surgeon would like to visualize in the absence of the monitor, and one or more augmented features are overlaid on the display. The graphical or video display data may be captured by one or more cameras in the surgical field of view. Enhancement features include, but are not limited to, a representation of the position of the tag in the target tissue, a projected surgical path, a target point at which the surgeon aligns the tip of the surgical device, a simulated surgical edge region to be treated, an arrow or other position indicator suggesting movement if deviated from the optimal path, and so forth.

An exemplary excitation assembly 250 is shown in fig. 4, 5, 6, and 7. As shown in fig. 1, the stimulating assembly may be located under a mattress of a patient lying on a surface, such as an operating table or mattress. The exemplary excitation assembly in these figures provides excitation signals to a tag within the patient via four excitation coils 150. The exemplary excitation assembly in fig. 4A provides a plurality of witness coil assemblies (also known as witness station assemblies) 161, each witness coil assembly having a witness coil 160 for detecting signals from an implanted tag and a tag in an attachment component attached to the surgical device. The excitation assembly consists of a base substrate 140 to which other components are substantially attached or integrated. The base substrate is composed of any suitable material, which may be, for example, polycarbonate or the like, and is generally non-magnetic and non-conductive. Not shown in fig. 4A is a top cover 230 (see fig. 8) that cooperates with the base substrate to enclose all internal components therein. The top cover is composed of any suitable material, including kevlar and/or other rigid materials, as well as being generally non-magnetic and non-conductive. Foam or other types of padding may be included on top of the top cover.

Four large excitation coils 150 are attached to the base substrate, which are labeled "coil a", "coil B", "coil C", and "coil D" in fig. 4A. Each excitation coil 150 may be wound on four excitation coil bases 155. In some embodiments, the excitation coil is not wound into any particular form, but rather employs wires that combine themselves to create a coil shape. Although not shown in fig. 4A, in certain implementations, a coil cover (e.g., a plastic coil cover) is located over each of the four excitation coils. A large central balun circuit 180 is located generally centrally between the four excitation coils.

The switch 190 is inside the exciting coils B, C and D. The switch 190 includes a component that controls the directionality (clockwise or counterclockwise) of the current in the respective excitation coils, such as a relay or a plurality of PIN diodes (e.g., at least four PIN diodes) or a field effect transistor. In the particular embodiment of fig. 4A, the excitation coil a does not have a switch 190, as the direction in the coil is unchanged. The switch 190 is connected to a differential capacitor for properly matching the different inductances caused by changing the directionality of the current. If one or more relays (e.g., four SPSTs, two SPDT types, or one DPDT) are used in the switch, the input is typically directed to one of the two outputs. If multiple PIN diodes are employed in switch 190 (to create a relay function), this provides a very high impedance when "off" and a low impedance when "on". Each switch 190 is also connected to one or more capacitors to modify the capacitance that forms a resonant circuit with the excitation coil inductor. This is necessary because when the current direction changes, the effective total series inductance of all excitation coils will also change. Also inside coils a-D are a pair of capacitor assemblies 195, which consist of a central container 197, flanked by metal leads 199. In certain embodiments, metal leads 199 are attached to a ceramic heat sink in order to dissipate heat that builds up during operation.

In operation, the actuation assembly in fig. 4A is configured to cycle between three configurations, referred to as configuration 1 (shown in fig. 5), configuration 2 (shown in fig. 6), and configuration 3 (shown in fig. 7), in certain embodiments. In configuration 1, as shown in fig. 5, the current from all four excitation coils is clockwise to simulate an excitation coil that is substantially aligned with a plane perpendicular to the Z-axis. In configuration 2, as shown in fig. 6, the current from coil a and coil B is clockwise, while the current from coil C and coil D is counter-clockwise, to simulate an excitation coil that is generally aligned with the Y-axis. In configuration 3, as shown in fig. 7, the current from coil a and coil C is clockwise, while the current from coil B and coil D is counter-clockwise, to simulate an excitation coil that is generally aligned with the X-axis. While this is a preferred embodiment, other combinations of coil polarities with other values of additional series capacitance may be advantageous for certain tag orientations. For example, the current in coil a may not be clockwise, but counter-clockwise, and then all other 3 coils (coils B, C and D) may have the current as shown in fig. 5, 6, or 7, or the other 3 coils (coils B, C and D) will have the opposite current as shown in fig. 5, 6, and 7. In other embodiments, the current arrangement is as shown in fig. 6, except that the current in coil B is in a counter-clockwise direction, and the current in coil D is in a clockwise direction. Each different combination of clockwise and counterclockwise coils a-D (i.e., all sixteen combinations) is contemplated.

The exemplary excitation assembly 250 in fig. 4A is also shown as having twelve witness station assemblies 161 (each witness station assembly having a witness coil 160). Twelve witness coils 160 alternate in opposite orientations (along the x-axis and y-axis) to reduce cross-talk. In other embodiments, software may also or alternatively be used to reduce crosstalk. In some embodiments, instead of alternating orientations, all witness coils are directed toward the center, which increases crosstalk, but may have the advantage of shifting the inflection point locations in witness coil signal pick-up as beacons shift across the perimeter of the excitation assembly. It is generally preferred that the wire feeding the excitation coil is not in close proximity to any witness coil to prevent isolation and reduction of noise pickup. In fig. 4A, the wires from the central balun circuit to each of the four excitation coils are located away from twelve witness coils 160. Also, as shown in FIG. 4A, witness coils extend downward from the left and right sides of the excitation assembly and do not span the top or bottom of the excitation assembly. Adding witness stations across the top and/or bottom may result in strong crosstalk. Alternatively, if witness coils are placed at the locations where crosstalk is induced, software applications may be used to reduce the crosstalk. Verification coil 160 is held in place by a pair of witness coil brackets 165.

Next to each witness coil 160 is a printed circuit board 170. Each printed circuit board 170 contains a capacitor and a small balun circuit. A capacitor is used with the witness coil to create a resonant circuit. Balun is used to eliminate common mode effects that would otherwise make witness coil assemblies susceptible to electric fields. It can also be used as an impedance matching element that matches the actual impedance of the coil/capacitor resonant circuit to the transmission line characteristic impedance (typically 50 ohms) by optimally selecting the primary and secondary turns.

Excitation assembly 250 in fig. 4A is also shown with a pair of self-test transmitters 220. These self-test transmitters 220 are present so that a known signal can be applied and the response on all witness coils checked. If the witness coil does not show the expected signal, it may indicate that there is a system problem or that there is a disturbing magnet or metal sheet that distorts the magnetic field and reduces the overall positioning accuracy. Note that another self-test that may be employed is to generate a signal on the excitation coil that is typically applied to one of the transmitters on the attachment component (e.g., sheath on the hand-held surgical device). The degree of isolation between each witness coil can be confirmed by measuring the signal transmitted from the exciter to them. In another self-test, a signal may be applied to each witness coil separately, while the remaining witness coils may be used to detect the signal. In other embodiments, field witness coil crosstalk may also be measured in this manner and used to calibrate the system.

Fig. 4A illustrates various wire connections between various components of the excitation assembly. Each witness coil 160 is attached to a coaxial cable that is connected to the system electronics housing (labeled "controller" 210) via cable bundle 200. The excitation signal enters the central balun circuit 180 from the cable bundle 200. From there, the conductors carry the signals to the switch 190 and/or the capacitor assembly 195. The system electronics housing (controller 210) performs signal processing (e.g., filtering, mixing, amplifying, digitizing, and demodulating of the multiple frequency 'channels') on the witness coil signal. Typically, no A/C primary power is applied to the witness coil.

With respect to the capacitors used in each capacitor assembly 195 and in the printed circuit board 170, generally, the capacitors are selected to be of the COG/NPO type, wherein the capacitance value does not change with temperature, such that the resonant frequency of the exciter does not change with temperature. The capacitor also provides a tuning network that can selectively increase the series capacitance to change the resonant frequency, which helps to reduce tolerances during manufacturing and makes it more tolerant of tuning variations due to temperature and other factors. In general, all materials used should have a high dielectric strength and a high stability with respect to temperature to prevent geometrical changes when the excitation assembly is used and the temperature is increased.

An exemplary witness coil assembly (also known as a witness station assembly) 161 is shown in fig. 4B. Witness coil assembly 161 includes two witness coil brackets 165 for clamping a fixed witness coil 160 to an elastomer 162. As shown in fig. 4B and 4C, witness coil 160 is comprised of a metal core (e.g., ferrite core) 166 and a coil 167 formed of wire. As shown in exemplary fig. 4C, the metal core 166 is comprised of a central region 173 (below the wire in fig. 4C) with a wireless proximal end 171 and a wireless distal end 172. Only the ferrite core (using wireless proximal and distal ends) is clamped by the bracket 165 and the elastomer 162 (e.g., to provide optimal alignment and eliminate the possibility of damaging the coil windings 167 of witness coil 160). The height of each end of witness coil 160 may be adjusted up and down by adjusting screw 163 (present in each witness coil support 165) while elastomer 162 provides a restoring force. The elastomer thickness and durometer are selected to provide the desired restoring force over the desired range of adjustment so that once the optimal position is reached, the adjustment screw can be easily adjusted, yet still maintain the desired setting. In addition, the coil brackets 165 each have a "V" or "U" shaped feature that allows them to secure the proximal and distal ends of the metal core 166. For example, this allows the bracket 165 to be precisely aligned with the witness coil core (e.g., ferrite core) in a desired direction, so that it cannot rotate about an axis perpendicular to the plane containing the excitation coil. Witness coil assembly 161 also includes a printed circuit board 170 (with a capacitor and balun circuit) and a faraday shield 168. The faraday shield may be composed of a conductive material such as brass or copper.

In certain embodiments, the excitation coil (e.g., as shown in fig. 4A) is connected to port 1 of a vector network analyzer or VNA. Witness coil output is typically connected to port 2 of the VNA and emissions are measured and displayed (S21). This measurement is a direct measurement of the signal present at port 2 resulting from the stimulus provided to port 1 and therefore of the isolation. The lower S21 (the larger the negative value) the better. The larger the negative value of S21, the better. Typical isolation values (S21) achieved by the generally preferred embodiments are-70 dB, with usable ranges including-50 dB to greater than-100 dB (e.g., noise floor of VNA).

In general, to achieve optimal isolation between the excitation coil and witness coil for optimal accuracy over a maximum navigation range, it is often important to locate the witness coil orthogonally (e.g., precisely orthogonally) to the magnetic flux generated by the excitation coil. Fig. 4A shows such an orthogonal arrangement of twelve witness coils. A slight deviation in the height or inclination of the witness coil from this optimal position will generally result in signal coupling from the excitation coil to the witness coil, which may impair isolation. Thus, in certain embodiments, a screw (or other connector) on the witness coil support is used for fine tuning.

Fig. 4C shows an exemplary witness 160 coil including how the coil 167 is formed by winding a wire around a metal core in three stages: i) A winding direction 1 in which the wire is wound on a majority of the front half of the metal core; ii) a winding direction 2 in which the wire is wound on top of the wire wound on the front half and on most of the rear half of the metal core; and iii) a winding direction 3 in which the wire is wound back on the wire on the latter half. In certain embodiments, there are 80-140 windings (e.g., 80 … 90 … 112 …) on each half of the metal core (e.g., 160-280 windings (e.g., 160 … 200 82348 224 … 280) in total.) in certain embodiments, the wire is a 32AWG copper magnet wire (e.g., 0.011 inch diameter) with a single layer polyester enamel and bond coat and the wire is secured during winding using heat.

The wires are also connected to the secondary of a miniature balun transformer (in the printed circuit board, part 170 in fig. 4B) by two series capacitors (e.g., on the printed circuit board), one for each wire in the coil. In general, in some embodiments, the total series capacitance is selected to resonate in combination with the inductance of the coil in the tag, and the turns ratio of the balun transformer may be selected to match the real impedance of the resonant coil/capacitor circuit to the real impedance of the transmission line (e.g., about 50 ohms). In certain embodiments, the real impedance of the resonant coil/capacitor circuit is typically 10 to 25 ohms, but can vary from only a few ohms to greater than 50 ohms and can be suitably matched by suitably selecting the primary and secondary turns of the balun transformer. In addition to acting as an impedance transformer, balun also minimizes any electric field generation/susceptibility from the witness coil assembly; alternatively, it may be considered to eliminate the common mode effect. To further reduce the electric field susceptibility, the use of a conductive faraday shield 168 over the balun and the capacitor is employed. The faraday shield (e.g., faraday cage) reduces the observed electric field of the components below the shield. Typically, faraday shields are used to reduce the emission of electric fields from components below the shield, in which case it may also reduce the reception of electric fields.

Fig. 8 shows the transmitter assembly 250 with the top cover 230 open. Top cover 230 may be composed of Kevlar fibers or other suitable rigid material. The excitation assembly 250 is shown with the cable bundle 200 drawn therefrom.

Fig. 9 shows an attachment member 10 having an angled distal end 300 through which the distal tip 25 of the medical device 20 is inserted. The display part 40 is attached to the attachment part control unit 310 via the attachment part line 60.

Fig. 10A shows distal end 25 of medical device 20 after initial insertion through angled distal end 300 of attachment member 10. This view is taken before the attachment member wires 60 are inserted into the cable management member 315. Fig. 10B shows the attachment member wires 60 prior to attachment to the cable management member 315 of the display member housing 330. Fig. 10B also shows a housing cone connector 340 into which the proximal cone connector 350 of the attachment member 10 is inserted. The cable management component 315 has two clips that align the fixation component wires 60 with the medical device wires 50.

Fig. 11 shows the attachment member 10 attached to the display member housing 330. The attachment member 10 has a pair of position transmitters 70 connected to position transmitter lead wires 72 inside the tube 360. Position transmitter 70 is powered by wire leads 72 to generate a signal that is detected by witness coils. The attachment member also has an angled distal end 300 with a distal opening 305 that allows the tip of a medical or other device to be inserted therein. The display member housing 330 has a cable management member 315 comprised of a pair of clips for holding attachment member wires and medical device wires.

Fig. 12 shows an exemplary attachment member 10 attached to a display member housing 330 in which a display member 40 is located. A display cover 370 is shown for securing the display assembly 40 within the display assembly housing 330. Also shown is an adhesive tape 380 (e.g., double sided tape with strong adhesive on both sides) shaped and sized to fit inside the attachment member and to help secure the medical device to the attachment member.

Fig. 14 illustrates an exemplary system for locating a tag implanted in a patient. The system consists of an excitation assembly that emits a signal that activates a tag within the patient. The system electronics housing is shown as a mobile cart that transmits signals to the excitation assembly and receives and processes signals from the position transmitters in the tag and attachment components within the patient. The guidance to the surgeon is displayed on the display component and on a screen on the housing of the system electronics.

Claims

1. A system, the system comprising:

a) A label;

b) A remote activation device that generates a magnetic field within an area of the tag, the remote activation device comprising a plurality of excitation coils, each excitation coil configured to flow a current in a clockwise or counter-clockwise direction such that the magnetic field generated by the remote activation device can be selectively generated substantially in an X-direction and a Y-direction; and

c) A plurality of sensors configured to detect a signal from the tag when the tag is exposed to the magnetic field, wherein each of the plurality of sensors includes a sensing axis that is coplanar with a central plane common to each of the plurality of excitation coils.

2. The system of claim 1, wherein the plurality of excitation coils is four excitation coils.

3. The system of claim 1, wherein the plurality of excitation coils are connected in series.

4. The system of claim 2, wherein the four excitation coils are presented in a layout arranged in two rows centered on coordinates (X1, Y1), (X1, Y2), (X2, Y1), and (X2, Y2).

5. The system of claim 4, wherein the remote activation device comprises three current flow configurations:

a) All currents are in a clockwise direction to simulate an excitation coil aligned or substantially aligned with a plane perpendicular to the Z-axis;

b) The excitation coil centered on (X2, Y1), (X2, Y2) causes current to flow in a counterclockwise direction to simulate an excitation coil aligned or substantially aligned with the X-axis; and

c) The excitation coils centered on (X1, Y2), (X2, Y2) cause current to flow in a counter-clockwise direction to simulate an excitation coil aligned or substantially aligned with the Y-axis.

6. The system of claim 1, wherein the remote activation device comprises a plurality of relays, at least one PIN diode, or field effect transistor that provide a switching function to maintain an excitation frequency.

7. The system of claim 6, wherein the switching function inserts an additional series capacitive reactance via a capacitive element as the total inductance increases such that the tuning center frequency is maintained at the excitation frequency.

8. The system of claim 7, wherein the capacitive element comprises a plurality of capacitors.

9. The system of claim 1, wherein the remote activation device further comprises a balun proximate the excitation coil.

10. The system of claim 1, wherein the magnetic field generated by the remote activation device is further selectively producible substantially in the Z-direction.

11. The system of claim 1, wherein the system further comprises an amplifier in electronic communication with the remote activation device.

12. The system of claim 1, comprising a plurality of tags.

13. The system of claim 1, further comprising a computer that controls magnetic field generation and sensor detection.

14. The system of claim 13, wherein the computer includes a trapping algorithm that adjusts the magnetic field orientation to identify optimal detection of one or more tags.

15. The system of claim 1, wherein the tag comprises an antenna, wherein the tag emits sidebands at defined frequencies after activation by a magnetic field.

16. The system of claim 15, wherein the tag antenna comprises a coil antenna.

17. The system of claim 16, wherein the coil antenna comprises a ferrite core coil antenna.

18. The system of claim 16, wherein the coil antenna resonates at 100-200 kHz.

19. The system of claim 16, wherein the coil antenna is coupled to an integrated circuit.

20. The system of claim 15, wherein the tag comprises a housing surrounding the tag antenna.

21. The system of claim 1, further comprising a medical device.

22. The system of claim 1, wherein at least one of the plurality of sensors comprises a witness station component, wherein the witness station component comprises:

a) Witness coil, wherein the witness coil comprises:

i) A metal core having a proximal end free of coils, a distal end free of coils, and a central region, an

ii) a coil winding wound on the central region of the metal core,

b) First witness coil support and second witness coil support, and

c) A first elastomer portion and a second elastomer portion,

wherein the wireless coil proximal end of the metal core is secured between the first witness coil stent and the first elastomeric portion, and

wherein the wireless coil distal end of the metal core is secured between the second witness coil bracket and the second elastomeric portion.

23. A method, the method comprising: a) Generating an excitation magnetic field using the remote activation device of the system of any one of claims 1 to 22; and b) detecting signals from the tag with the plurality of sensors.

24. The method of claim 23, wherein the excitation magnetic field is generated in one of an X-plane or a Y-plane and the sensor detects the tag signal in a plane substantially perpendicular to one of an X-direction or a Y-direction.

25. Use of the system of any one of claims 1 to 22.

26. Use of a system according to any one of claims 1 to 22 for detecting the position of a tag in an object.

27. Use of the system of any one of claims 1 to 22 for detecting the position of a tag relative to a medical device.

28. The system of claim 1, wherein the magnetic flux generated by the remote activation device does not induce a signal in the plurality of sensors.